Such form panels are known in a wide spectrum of forms. Marginal sections having a hollow cross-section produce good stiffness and can be fastened together with the aid of clamps. It is important that these marginal sections, which must sustain high forces, also be connectable with corresponding security and firmness to the lining skin itself, in order that the respective flux of force is also attained there.
Such formwork is known, for example, from German Patent DE 38 38 488 C2. The marginal sections, provided with a closed, approximately rectangular hollow cross section, have in the holding web a channel-like depression for application of a clamp, as is known by way of example from German Utility Model No. 88 14 208. Such a clamp is made to conform to double the size of a hollow marginal section and can bring about only a frictional connection.
In many cases, however, it may be suitable for form panels of the formwork to have not only marginal sections with a hollow cross section, but also marginal strips consisting of flat material, this being advantageous particularly if and when, for instance, form panels variable in their curvature are to be combined with flat form panels. The clamps permitting a specific closing travel are unsuited for such combinations of a hollow marginal section with a marginal strip consisting of flat material.
Hitherto, such form panels with only flat marginal strips have been connected, as a rule, by connecting bolts conforming generally to German Patent No. 21 37 505. However the clearance between projections jutting out at right angles to the bolt surface and counter-stops is too small for these connecting bolts to be able to traverse marginal sections having a hollow cross section.
A proposal has become known from German Patent DE 38 38 509 C1 that two marginal sections having a hollow cross section be traversed in a direction parallel to the lining skin and thereby be connected by a relatively long and elaborate bolt. However, this requires that the hollow sections have through holes which either weaken them or have to be furnished with sleeves inside the marginal sections as a guide for the respective bolt, increasing the manufacturing expenditure accordingly.